Apparatus for conversion of reciprocating motion into rotating motion

ABSTRACT

A transmission for conversion of a reciprocating movement into a rotating movement, particularly for use in an electronic timepiece having a time-keeping mechanical resonator, and wherein synchronization between the reciprocating movement and rotating movement and starting of the rotating movement in a perfectly defined direction is obtained by suitable shaping of cams of a track of ferromagnetic material facing a magnetized reciprocating element.

United States Patent Gaston Raval Inventor La Neuveville, Switzerland Appl. N 0. 867,224 Filed Oct. 17, 1969 Patented Feb. 23, 1971 Assignee Omega Louis Brandt & Frere S. A. Biel, Bern, Switzerland Priority Nov. 2, 1968 Switzerland 16,358/68 APPARATUS FOR CONVERSION OF RECIPROCATING MOTION INTO ROTATING MOTION 16 Claims, 9 Drawing Figs.

U.S. Cl. 310/21, 58/23, 58/116 Int. Cl H02k 7/06 Field of Search 310/20, 21,

22,103, 80; 58/23, 23 (TF), 116, l 16 (M), (Inquired); 74/(Inquired) [56] References Cited UNITED STATES PATENTS 2,554,523 5/1951 Clifford 58/116X 2,654,989 10/1953 Nichols 58/116 2,690,646 10/1954 Clifford 58/116 3,171,991 3/1965 Baumer 310/21 Primary ExaminerD. F. Duggan Attorny-Imirie & Smiley PATENTEUFEB23 1971 FIGS FIGJL FIGS FIG .2

INVENTOR.

. GASTON 'RAVAL Att.'r.s.

APPARATUS FOR CONVERSION OF RECIPROCATING MOTION INTO ROTATING MOTION This invention relates to a transmission for conversion of a reciprocating movement of a resonator into a rotating movement. Transmissions of this type are used for example in timepieces including a time-keeping tuning fork, for conversion of the vibrating movements of the tuning fork into a rotation suitable for driving the hands of the timepiece. The prior The shaft 6 has a worm l2 meshing with a toothed wheel 13 of the gear train driving the hands of the timepiece. When the pawl transmissions are delicate and have to be mounted and adjusted by experts.

In order to avoid these disadvantages of pawl transmissions magnetic transmissions have been proposed comprising at least one magnetized element reciprocating together with said resonator and an indexing wheel having a profiled track of ferrornagnetic material facing said element. Prior transmissions of this type have a magnetized element facing a nonmagnetized track of soft iron. Their starting direction is not well defined so that such transmissions requirean auxiliary starting mechanism for starting them in the desired direction.

This invention aims in avoiding the above drawbacks in a simple and efficient manner. The transmission according to this invention broadly comprises at least one magnetized ele' ment adapted for reciprocating movement with said resonator and an indexing wheel having a track of ferromagnetic material facing said magnetized element and composed of two rims of cams separated from each other by airgaps and staggered in circumferential direction, said element being adapted to swing axially over said cams and a salient portion of each cam being separated from a neighboring cam of the other track by an airgap near the neutral position .of said magnetized element. Under these conditions it is possible to obtain starting of the indexing wheel in a well defined direction because each cam of the track sticks or adheres to the element reciprocating due to the magnetic attraction until the element jumps over the relatively narrow airgap in a well determined direction, whereafter the next cam adheres to the element until the element jumps over the next airgap in v a well determined direction. It is thus possible to dispose the cams and airgaps in the manner of a railway-switch system by which the magnetized element may only advance in a well defined direction along the track. 7

One embodiment of the invention and a number of modifications will now be explained, by way of example, with reference to the accompanying drawing, wherein:

FIG. 1 schematically shows the embodiment,

FIG. 2 is a development of the cam tracks of the transmission of FIG. 1, and

FIGS. 3 to 9 illustrate modifications of cam tracks.

The embodiment schematically illustrated in FIG. 1 has a U- shaped permanent magnet i fixed in a manner not shown on the one leg of a tuning fork not shown in the drawing. Preferably a tuning fork of substantially semicircular form is used which allows a favourable utilization of the space disposable in a timepiece and of which the ends of the legs and the magnet I fixed thereto execute a substantially rectilinear reciprocation. The permanent magnet 1 has two poles 2 and 3 facing an indexing wheel 4. This wheel comprises a supporting disc 5 fixed on a shaft 6 pivotably mounted in bearings not shown in the drawing. Two discs 7 and 8 of ferromagnetic material are fixed on the supporting disc 5. Each of discs 7 and 8 has a-rim 9 whereon is formed a track of cams of the shape disclosed in FIG. 2. By cutting 10 of trapezoidal shape T- shaped cams 11 are formed. The transversal or axial branches of such cams are of flat triangular shape while the circumferentially extending branches interconnect successive cams of each track. The rims 9 of discs 7 and 8 and the tracks of cams respectively formed on said rims axially engage into each other, the cams being staggered in circumferential direction as shown in FIG. 2. A system of cams separated from each other by cuttings 10 is obtained in this way. Manufacture of this indexing wheel is relatively simple because discs 7 and 8 may be cut separately and then assembled on support -5.

permanent magnet 1 reciprocates, its poles 2 and 3 are axially displaced at an amplitude slightly lower than half the axial width of the indexing wheel 4.

In this embodiment the poles 2 and 3 are of the same polarity, for instance S and all cams 11 of both rims 9 are permanently magnetized in opposite polarity, for instance N. Therefore, each of poles 2 and 3 of the element 1 attracts one of the earns 11 and each cam 11 sticks or adheres to the pole 2 or 3 facing it as long as this pole does not leave the cam in axial direction. These cams are attracted and pulled downwards in FIG. 2 when the pole 2 or 3 of element 1 swings in axial direction along one of the lower inclined sides of the cam. In this way each pole is near the upper straight side of each cam when it leaves the cam at its inner end, and then the pole necessarily enters the lower portion of the next cam of the other track. Consequently, this next cam is now attracted and displaced downwardly in FIG. 2, and the pole will leave this cam along its upper inner end or salient portion and will enter through the airgap into the lower portion of the next cam of the other track. In this way the indexing wheel is positively displaced by the reciprocating poles of element 1 in a direction well determined, namely downwardly in the development shown in FIG. 2. The relative displacement of each pole along the cams of the indexing wheel is indicated in a dash-dotted line in FIG. 2. It is seen that it is practically a sinusoidal line, that is, the indexing wheel is advanced at a pratically constant speed. Rotation of the indexing wheel is transmitted through shaft 6, worml2, and worm wheel 13 to the gear train of the timepiecefor driving the hands.

FIG. 3 illustrates a modified form of tracks. In this case the cams 11 are completely separated from each other by cuttings 14. By this separation of the cams it is possible to obtain even more definite starting conditions and more efficient torque transmission to the wheel.

FIG. 4 illustrates another modification of the cam tracks 15. The cams have an outer axial portion and an inner inclined portion. Each of these cams sticks or adheres to a pole 2 or 3 until the pole leaves the cam in a definite direction through one of the airgaps 16 formed between the inner end of each cam and the angle of the adjacent cam. In this way definite starting and driving of the indexing wheel in a predetermined direction is obtained.

The modification shown in FIG. 5 differs from the one illustrated in FIG. 4 in that the inner ends of the cams 17 are of triangular shape. Operation is practically the same as for the modification of FIG. 4.

FIG. 6 illustrates another modification with axially extending cams 18 having pointed inner ends or salient portions.

FIG. 7 shows a modification with straight inclined cams 19. The poles 2 and 3 cannot leave these cams in another direction than from their inner upper end towards the next upper cam of the other track, whereby starting and driving in a predetermineddirection is obtained.

The modification of FIG. 8 is similar to the one shown in FIG. 7, but the inclined cams 20 axially engage into each other.

The modification illustrated in FIG. 9 has some similarity with the one of FIG. 3, but the cams 21 of substantially triangular form have rounded inner ends and slightly curved airgaps. Most of the modifications illustrated in the drawing may be manufactured by relatively simple cutting, particularly when the indexing wheel is composed of two discs in the manner disclosed in FIGS. 1 to 7, but other manufacturing processes may be used. As an example, the modification shown in FIG. 9 or any other embodiment may be manufactured by chemical or electrochemical etching or erosion or any other suitable method.

Iclaim:

l. A transmission for conversion of a reciprocating movement of a resonatorinto a rotating movement, comprising at least one magnetized element adapted for reciprocating movement with said resonator and an indexing wheel having a track a of ferromagnetic material'facing said magnetized element and ing cam of the other track by an airgap near the neutral position of said magnetized element.

2. A transmission according to claim 1, wherein at least the rear sides with reference to the rotating direction of the wheel of said salient portions are inclined toward the inside of the track in a determined circumferential direction.

3. A transmission according to claim 1, wherein said indexing wheel is made of two discs of which the rims have cams formed by airgaps cut into the rims.

4. A transmission according to claim 3, wherein said rims are of larger axial thickness than the remaining parts of said discs, said rims and cams respectively axially engaging into each other. v

5. A transmission according to claim 2, wherein said cams have an outer axial portion and an inner inclined portion.

6. A transmission according to claim 2, wherein said cams have an axial outer portion and an inner triangular portion.

7. A transmission according to claim 6, wherein the axial portion is staggered in circumferential direction relatively to said triangular portion.

8. A transmission according to claim 2,-comprising two rims of inclined cams 9. A transmission according to claim 2, comprising cams of substantially triangular shape having an axially extending straight side and two inclined sides.

10. A transmission according to claim 2, comprising T- shaped cams, the transver sal portion of the T being of flat triangular shape having a straight axial side and two inclined sides.

11. A transmission according to claim 10, wherein the cams of each rim are interconnected without airgap by their circumferential portions of the T. Y

12. A transmission according to claim 1, wherein said element is a permanent magnet of U-shape having two poles facing diametrically opposite places of the indexing wheel.

13. A transmission according to claim .1, wherein all cams of the indexing wheel are permanently magnetized with the same polarity of all cams at their surface facing said element.

- 14. A transmission according to claims 12 and 13., wherein said element has two poles of same polarity facing the indexing wheel.

15. A transmission according to claim 14, wherein said element and said cams are of opposite polarity thereby producing attracting forces between said element and said cams.

16. A transmission according to claim I, wherein said salient portions axially extend over the centerline of said indexing wheel. 

1. A transmission for conversion of a reciprocating movement of a resonator into a rotating movement, comprising at least one magnetized element adapted for reciprocating movement with said resonator and an indexing wheel having a track of ferromagnetic material facing said magnetized element and composed of two rims of cams separated from each other by airgaps and staggered in circumferential direction, said element being adapted to swing axially over said cams and a salient portion of each cam being separated from a neighboring cam of the other track by an airgap near the neutral position of said magnetized element.
 2. A transmission according to claim 1, wherein at least the rear sides with reference to the rotating direction of the wheel of said salient portions are inclined toward the inside of the track in a determined circumferential direction.
 3. A transmission according to claim 1, wherein said indexing wheel is made of two discs of which the rims have cams formed by airgaps cut into the rims.
 4. A transmission according to claim 3, wherein said rims are of larger axial thickness than the remaining parts of said discs, said rims and cams respectively axially engaging into each other.
 5. A transmission according to claim 2, wherein said cams have an outer axial portion and an inner inclined portion.
 6. A transmission according to claim 2, wherein said cams have an axial outer portion and an inner triangular portion.
 7. A transmission according to claim 6, wherein the axial portion is staggered in circumferential direction relatively to said triangular portion.
 8. A transmission according to claim 2, comprising two rims of inclined cams.
 9. A transmission according to claim 2, comprising cams of substantially triangular shape having an axially extending straight side and two inclined sides.
 10. A transmission according to claim 2, comprising T-shaped cams, the transversal portion of the T being of flat triangular shape having a straight axial side and two inclined sides.
 11. A transmission according to claim 10, wherein the cams of each rim are interconnected without airgap by their circumferential portions of the T.
 12. A transmission according to claim 1, wherein said element is a permanent magnet of U-shape having two poles facing diametrically opposite places of the indexing wheel.
 13. A transmission according to claim 1, wherein all cams of the indexing wheel are permanently magnetized with the same polarity of all cams at their surface facing said element.
 14. A transmission according to claims 12 and 13, wherein said element has two poles of same polarity facing the indexing wheel.
 15. A transmission according to claim 14, wherein said element and said cams are of opposite polarity thereby producing attracting forces between said element and said cams.
 16. A transmission according to claim 1, whereiN said salient portions axially extend over the centerline of said indexing wheel. 